By Kristin Roberts

WASHINGTON, Aug 7 (Reuters) Gays in the US military face regular hostility on some bases and ships where commanders fail to prohibit harassment more than a decade after the ''Don't Ask, Don't Tell'' law was enacted, although seeds of greater tolerance may be taking root, advocates and witnesses report.

While some leaders have created environments where harassment is not tolerated, others have not and the evidence, according to witnesses, is both verbal and visual.

On the Navy's USS Theodore Roosevelt aircraft carrier, for example, anti-gay statements and jokes are on display and have been incorporated into a video about the F-14 Tomcat fighter aircraft, recently shown to reporters on the carrier.

Pilots on the Roosevelt sported T-shirts, also shown to reporters including this Reuters correspondent, that said, ''I'm a Tomcat guy and you're a homo.'' The commander of the fighter squadron, in fact, wore the shirt.

''The line between that and threats and violence can be quite thin,'' said Aaron Belkin, director of the Center for the Study of Sexual Minorities in the Military at the University of California-Santa Barbara.

Openly gay people are prohibited from serving in the US military under a 1993 law known as ''Don't Ask, Don't Tell.'' The military can't ask if a service member is gay, but those who say they are gay are discharged.

The US military argues that banning gays from the military is critical to maintaining a unit's ''cohesion,'' the trust among service members crucial to combat effectiveness.

Harassment of gays, however, is prohibited. The Pentagon, in a 2000 memo to the armed services and commanders, said ''mistreatment, harassment and inappropriate comments or gestures'' based on sexual orientation were not acceptable.

That followed a report from the Defense Department's inspector general that found 80 per cent of service members surveyed had heard anti-gay comments and 37 per cent had witnessed harassment against people thought to be homosexual.

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