SEOUL, March 9 (UPI) — The United States and South Korea began their annual Freedom Shield joint military exercise on Monday, as speculation swirled that Washington may be shifting some military assets from the Korean Peninsula to the Middle East amid its widening conflict with Iran.

About 18,000 South Korean troops will participate in the exercise, which runs through March 19 and includes command-post simulations and field training drills. U.S. Forces Korea has not disclosed the number of American personnel involved.

The drills come as local media reports have raised questions about whether U.S. military equipment stationed in South Korea could be redeployed to support operations in the Middle East.

South Korea’s Yonhap News Agency reported Sunday that U.S. C-5 and C-17 transport aircraft landed at Osan Air Base in Pyeongtaek, south of Seoul, late last month before departing between Wednesday and Saturday.

The aircraft movements followed reports that U.S. Forces Korea relocated some Patriot missile defense systems to Osan from other American bases in the country.

Two Patriot batteries deployed with USFK were temporarily rotated to the Middle East in June last year during strikes targeting Iranian nuclear facilities, before returning to South Korea in October.

The Patriot system detects, tracks and intercepts drones, cruise missiles and short-range or tactical ballistic missiles at low- to mid-range altitudes. It forms a key component of South Korea’s layered missile defense network designed to counter threats from North Korea.

U.S. Forces Korea said last week it could not comment on the relocation or movement of its assets due to operational security.

South Korea’s Defense Ministry also declined to address the reports directly during a briefing Monday.

“There is constant communication between the U.S. military and our side,” ministry spokeswoman Jeong Bit-na told reporters. “We are always communicating closely to ensure that there are no security concerns or gaps.”

She added that the Freedom Shield exercise was proceeding as planned.

“The South Korea-U.S. joint exercise is being implemented normally regardless of the situation in the Middle East, and we are thoroughly implementing it as agreed and planned,” Jeong said.

The drills come as the administration of South Korean President Lee Jae Myung seeks to stabilize relations with Pyongyang, which routinely condemns the allies’ joint exercises as rehearsals for invasion.

The number of field training exercises during this year’s Freedom Shield has been reduced to 22, down from 51 conducted during the previous iteration of the drills under the conservative government of impeached former President Yoon Suk Yeol.

North Korea recently concluded a major congress of the ruling Workers’ Party, where leader Kim Jong Un pledged to expand the country’s nuclear arsenal and improve its delivery systems and operational capabilities.

At the same time, Kim appeared to leave the door open to future negotiations with the United States, saying there was “no reason” the two sides could not improve relations if Washington abandons what he described as its hostile policy.

Kim has previously said he has “fond memories” of U.S. President Donald Trump, whom he met three times during Trump’s first term. South Korean officials have pointed to Trump’s planned visit to China later this month as a possible opportunity to revive diplomacy with Pyongyang.

Kim has continued to take a hostile tone toward Seoul, however, recently describing South Korea as “the most hostile entity.”