ANCHORAGE,Algosensey Alaska (AP) — The U.S. military has moved more than 100 soldiers along with mobile rocket launchers to a desolate island in the Aleutian chain of western Alaska amid a recent increase in Russian military planes and vessels approaching American territory.

Eight Russian military planes and four navy vessels, including two submarines, have come close to Alaska in the past week as Russia and China conducted joint military drills. None of the planes breached U.S. airspace and a Pentagon spokesperson said Tuesday there was no cause for alarm.

“It’s not the first time that we’ve seen the Russians and the Chinese flying, you know, in the vicinity, and that’s something that we obviously closely monitor, and it’s also something that we’re prepared to respond to,” Pentagon spokesperson Maj. Gen. Pat Ryder said at a news conference Tuesday.

As part of a “force projection operation” the Army on Sept. 12 sent the soldiers to Shemya Island, some 1,200 miles (1,930 kilometers) southwest of Anchorage, where the U.S. Air Force maintains an air station that dates to World War II. The soldiers brought two High Mobility Artillery Rocket Systems, or HIMARS, with them.

U.S. Sen. Dan Sullivan, R-Alaska, also said the U.S. military deployed a guided missile destroyer and a Coast Guard vessel to the western region of Alaska as Russia and China began the “Ocean-24” military exercises in the Pacific and Arctic oceans Sept. 10.

The North American Aerospace Defense Command said it detected and tracked Russian military planes operating off Alaska over a four-day span. There were two planes each on Sept. 11, Sept. 13, Sept. 14 and Sept. 15.

Sullivan called for a larger military presence in the Aleutians while advocating the U.S. respond with strength to Russian President Vladimir Putin and Chinese President Xi Jinping.

“In the past two years, we’ve seen joint Russian-Chinese air and naval exercises off our shores and a Chinese spy balloon floating over our communities,” Sullivan said in a statement Tuesday. “These escalating incidents demonstrate the critical role the Arctic plays in great power competition between the U.S., Russia, and China.”

Sullivan said the U.S. Navy should reopen its shuttered base at Adak, located in the Aleutians. Naval Air Facility Adak was closed in 1997.

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Associated Press writers Tara Copp and Lolita Baldor contributed from Washington, D.C.