NORFOLK, Va. — Navy sailors will suit up in battle gear and take up fighting positions at U.S. bases during the country's largest anti-terrorism exercise, an effort meant to gauge their response to multiple attacks, officials said.

Navy installations in the continental U.S., Guam and Hawaii will participate in Exercise Solid Curtain-Citadel Shield from Tuesday through Friday, giving officials a snapshot of military readiness as the 10th anniversary of the Sept. 11 attacks approaches.

The Navy plans to simulate real-world threats, incorporating lessons learned from the 2000 bombing of the Navy destroyer USS Cole and the 2009 Fort Hood shooting, among others.

Security officials will track scores of potential threats and sailors' responses to them from a control room at Naval Station Norfolk, the world's largest naval base.

The exercise will replicate a variety of scenarios, from an explosive going off in San Diego to a bomb threat at a recruiting centre. The public may see people in battle gear with guns, military dogs and fixed fighting positions manned at some bases.

"You want to train the way you fight, so if you don't make it real you're not getting the full training that you not only should get, you have to get out of it," said Capt. Sam McCormick, U.S. Fleet Forces director for fleet anti-terrorism.

The Navy said the annual exercise involving more than 250 scenarios isn't a response to a specific threat but helps identify where forces are vulnerable. A review last year found that some things could be improved, McCormick said.

"You have ships personnel trying to co-ordinate with security personnel on the shore that we found, quite frankly, we could do it a little better," he said.

All facilities will have heavy security, and traffic delays are likely near many bases. Recreational boaters will also likely see tighter security along the Navy's waterfront.

Army and Marines Corps officials also will observe the exercise, which is being co-ordinated by U.S. Fleet Forces Command.