The U.S. dollar has made a nice upward move during the last three weeks, but that rise may not be over just yet.

The greenback has been helped along by the renewed fears about European debt as investors seek the safety of the U.S. currency.

The latest confrontation between North and South Korea certainly isn’t helping to calm investor uneasiness either.

While these concerns have certainly helped spur the rally in the dollar, it isn’t the reason I think the rally could continue.

In addition to the Dollar Index crossing bullishly above its 100-day moving average, the sentiment toward the dollar has barely moved.

Two months ago, the large speculators moved into a net short position for the first time in the previous year. The group started adding net long positions a few weeks before the rally in the dollar started, but they are only long a little over 10,000 contracts. The biggest net long position over the last five years is all the way up at 42,000 contracts.

With the potential for the European debt crisis to continue for some time and the potential for large speculators to continue adding to their long positions, I wouldn't be betting against the dollar falling any time soon.