What can be done if an ex takes child across state lines without the other parents permission?

My husband and his ex have joint legal custody of their daughter. In their child custody decree it is stated that for either parent to take the child across state lines, that they must have written permission from the other parent. We've recently discovered that his ex is planning an out of state trip in about a month. My husband does not want to consent due to the knowledge of who she's planning on visiting. Part of the problem right now is that my husband has just deployed. If he were home and she took their daughter regardless of his wishes, he would call his atty and deal with it that way. Unfortunately with him being deployed may not be able to do that. If he has papers drawn against her when he returns is it too late? Can his atty file papers even though he isn't in the country?