As tensions remain high in the Middle East, the US military is preparing for a number of potential contingencies in the key arena of the Arabian Sea that may arise during a regional conflict.
The Iranian regime continues to pursue a destabilising agenda, mainly through the use of proxy militias in Iraq, Syria, Lebanon and Yemen. In addition to training, it provides them with illegal weapons smuggled in by air, land and sea.
Meanwhile, in late May, the UN nuclear watchdog voiced concern that Iran had not clarified queries over possible undeclared nuclear activity, adding that its enriched uranium stockpile was 16 times over the allowed limit.
These steps, among others, constitute violations of the 2015 nuclear deal that Iran signed with global powers, even as Tehran reconsiders the deal.
In the face of escalating tensions and threat of military conflict in the region, the United States, aided by allies throughout the region and around the globe, is policing sensitive waterways ranging from the narrow Strait of Hormuz to the sprawling Arabian Sea.
For example, the guided-missile cruiser USS Monterey during a two-day operation on May 6-7 intercepted a stateless dhow sailing in international waters of the North Arabian Sea. Search teams found a huge cache of illicit Russian and Chinese weapons onboard.
A US defence official, who spoke on condition of anonymity to discuss the ongoing investigation, told the Associated Press that the Navy's initial investigation found the vessel came from Iran.
The weapons found aboard the vessel resembled those of other interdicted shipments bound for the Iran-backed Houthis in Yemen, he added.
To prepare for such contingencies in the Arabian Sea, the United States, France, Belgium and Japan conducted a multilateral joint exercise earlier in March.
Group Arabian Sea Warfare Exercise took place in the Arabian Sea and Gulf of Oman March 19-22.
"During the exercise, participating forces focused on the full spectrum of maritime warfare operations, practicing anti-air warfare (AAW), anti-surface warfare (ASUW), and anti-submarine warfare (ASW) tactics and procedures," said a statement from US Central Command (CENTCOM).
Led by France's Charles De Gaulle carrier strike group, the exercise included the amphibious assault ship USS Makin Island with F-35B Lightning II joint strike fighters and MV-22 Osprey tiltrotor aircraft from the 15th Marine Expeditionary Unit.
Other US assets included the guided-missile cruiser USS Port Royal, P-8A Poseidon multi-mission aircraft and US Air Force E-3 Sentry airborne warning and control system aircraft, the statement said.
The Arabian Sea has an area of about 3.9 million sq. km and a maximum depth of more than 4.6km in some locations.
The Gulf of Aden in the west connects the Arabian Sea to the Red Sea through the Strait of Bab al-Mandeb. The Gulf of Oman, to the northwest, connects it to the Arabian Gulf through the Strait of Hormuz.
To remain ready for any contingencies, the United States has maintained strategic partnerships in the region, including with Oman.
Situated along the Arabian Sea, Oman sits on the southern approach to the Strait of Hormuz, across from Iran.
Oman has been a strategic partner of the United States since 1980, when it became the first Gulf state to sign a formal accord permitting the US military to use its facilities, according to a report last June from the US Congressional Research Service.
The agreement, revised in 2010, allows the United States access to Oman's military airfields in Muscat, Thumrait, Masirah Island and Masnaah.
In March 2019, officials further expanded that agreement to allow US forces to use the ports of Duqm and Salalah.
Duqm, situated in southern Oman on the Arabian Sea, about 500km from the Strait of Hormuz, is large enough to handle US aircraft carriers and improves the United States' ability to counter Iran, according to US officials.
At the mouth of the Gulf, the strait is crucial to global energy supplies, with about a third of the world's seaborne oil passing through it every day.
On a visit to Oman in February, Gen. Kenneth McKenzie, the commander of US CENTCOM, urged Iran not to undertake any "nefarious activities" as it seeks to rebuild trust.
"We will be prepared for any eventuality, however," he added.
Keeping watch over the Arabian Sea is the US 5th Fleet, which is responsible for an area of operations encompassing about 6.5 million sq. km of water and includes the Arabian Gulf, Red Sea, Gulf of Oman and parts of the Indian Ocean.
As tensions with Iran ramped up late last year, the United States staged a surge of assets into the region.
Those assets included seven flights of B-52 bombers to the Persian Gulf, the extended deployment of the USS Nimitz aircraft carrier and the transit of nuclear-powered guided-missile submarine USS Georgia through the Strait of Hormuz.
"The United States continues to deploy combat-ready capabilities into the US Central Command area of responsibility to deter any potential adversary, and make clear that we are ready and able to respond to any aggression directed at Americans or our interests," McKenzie said on December 30 following a bomber flyover.
"We do not seek conflict, but no one should underestimate our ability to defend our forces or to act decisively in response to any attack," he said.
After the USS Nimitz left the region in February, the USS Dwight D. Eisenhower aircraft carrier along with guided-missile cruiser USS Monterey and guided-missile destroyers USS Mitscher and USS Thomas Hudner transited the Suez Canal into the Red Sea on April 2, said a US Navy statement.
Since then, the Eisenhower Strike Group has been operating in the North Arabian Sea, USNI News reported.
The United States also has a number of military bases across the Gulf -- the largest in Qatar.